US 2013/0233287 A1 discloses a vapor return system with a fuel vapor collecting tank in which a vapor outlet line can be fitted onto a suction inlet of a venturi nozzle by way of a stop valve. The venturi nozzle is either integrated into the charge air duct or situated in a bypass line, which circumvents a throttle flap in the charge air duct, and thus requires an additional parallel throttle flap in the bypass fine. The charge air pressure is diminished over the entire fuel vapor collecting tank evacuation period via the bypass flow for the venturi nozzle by bridging the throttle flap in the charge air duct.